Cigarette filter element containing water-soluble monomeric hydrazides for the selective removal of aldehyde vapors



Dec. 26, 1967 LEONARD ET AL 3,359,990

CIGARETTE FILTER ELEMENT CONTAINING WATER-SOLUBLE MONOMERIC HYDRAZIDES FOR THE SELECTIVE REMOVAL OF ALDEHYDE VAPORS I Filed Oct. 29, 1965 FIG! CIGARETTE WRAPPER F IL TE R WRAPPER TOBACCO FILTER COATED WITH WATER- SOLUBLE MONOMERIC HYDRAZIDES FIG- 2 COATING OF WATEB SOLUBLE HYDRAZIDE FILTER TOBACCO SMOKE FLOW FIBERS T RAY E- LEONARD GEORGE P- TOUEY INVENTORS' BY %MM ATTORNEY? E E United States Patent CIGARETTE FILTER ELEMENT CONTAINING WA- TER-SOLUBLE MONOMERIC HYDRAZIDES FOR THE SELECTIVE REMOVAL OF ALDEHYDE VAPORS Ray E. Leonard and George P. Touey, Kingsport, Tenn., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed Oct. 20, 1965, Ser. No. 498,946 17 Claims. (Cl. 131-267) This invention relates to a tobacco smoke filtering material for selectively removing deleterious materials from tobacco smoke without .at the same time removing those desirable smoke vapors which contribute aroma and taste to the smoke. More particularly, this invention concerns a novel cigarette filter tow and filters made therefrom, as well as the method for their manufacture, which Will selectively remove aldehyde from tobacco smoke.

The harmful physiological effects of volatile constituents contained in tobacco smoke have long been recog nized. It is well known, for example, that tobacco smoke contains certain solid tar constituents and health-affecting volatile materials of the nicotine class which tend to physiologically irritate the smoker. In the past, various attempts have been made to obviate these harmful materials from tobacco smoke by either using various types of tobacco smoke filters attached to the smoking device, or incorporating certain preventive compounds into the tobacco being smoked. As of the present time the use of a tobacco smoke filter element placed on the tip of the smoking device is the method or device most commonly used for removing these undesirable components from tobacco smoke. These filters, which normally consist of a bundle of cellulosic fibers or convoluted creped paper formed into a cylindrical plug, are designed to and do remove varying proportions of the droplets and solid particles passing through them thereby greatly reducing the amount of undesirable materials reaching the smokers mouth. This solid particle filtering action is accomplished by a combination of diffusional, impactive, and direct collision of the droplets with the filter materials. Upon collision the droplets are retained in the filter by the surface attraction between the extremely small particles and the relatively large filter material.

However, since these fibrous filters work on the principle of entrapment and condensation, the undesirable gaseous components such as, for example, acetaldehyde and acrolein found in tobacco smoke cannot be removed by such filters. These gaseous acetaldehyde and acrolein components of tobacco smoke merit special attention since they have been found to be highly irritating to the smoker and contribute to the inhibition of the action of the ciliated cells which line the trachea and bronchioles. The cilia of these cells rhythmically beat to and fro, and by this action carry foreign bodies up and out of the respiratory tract thereby preventing such foreign particulate matter from accumulating in the respiratory system. When the activity of the cilia is inhibited by the deleterious gases in tobacco smoke, the smoke particles, including any tar particles contained in the smoke, will pass by the less active or quiescent cilia and collect in the lungs or other parts of the respiratory tract.

In attempts to improve the ciliary depressant removal properties of tobacco smoke filters, various treatments of the filtering material, and certain new filtering materials have been propose-d and tried. Among the materials and treatments proposed for use in or with the tobacco smoke filters was a number of well-known adsorbents such as activated charcoal, alumina, natural and synthetic clay, and silica gels. Such adsorbent-containing tobacco smoke filters are effective to some extent in removing ciliary depressants from the vapor phase of cigarette smoke, but their use has some definite disadvantages. For example, such adsorbent additives indiscriminately remove from the tobacco smoke not only certain obnoxious or toxic components, but many other components as well which are necessary to maintain the desired flavor and aroma of the smoke. In the case of activated carbon, which at the present time is the most commonly used adsorbent additive, the removal of these flavoring agents imparts an undesirable taste to the smoke that is commonly referred to as the carbon taste. Furthermore, since the adsorption of vapors by these materials is based on physical phenomenons which are in turn dependent upon temperature and pressure many of the adsorbed vapors including those that are deleterious may later be released in concentrated quantities as the burning zone of the cigarette approaches the filter during the smoking of the cigarette. If enough carbon is used in the filter to compensate for this deficiency the cigarette becomes for all practical purposes unsmok-able.

In an effort to overcome certain of the inherent disadvantages of those prior known and used filter materials which neither selectively adsorb predetermined deleterious constituents nor chemically reduce the materials that are adsorbed, it has been proposed that certain solid additives including polymeric hydrazides be dusted into the filters. Although these materials are more selective in their removal of aldehyde type gases from tobacco smoke they are extremely difiicult to apply to the filter during its manufacture. For example, these materials are granular in nature and must, for best results, be applied to the filter tow by a dusting or like action. Such an application step not only produces a house cleaning problem as well as a potentially explosive condition, but also requires the use of special, rather expensive and bulky processing equipment. However, even when such equipment is used by highly skilled personnel it has been found that it is nearly impossible to obtain a uniform distribution of the finely-divided additive. Furthermore, these additives have a tendency to sift out of the filter thus creating a dirty appearance on the filter tip as well as entering the smokers month, which, needless to say, is most objectionable. The use of a bonding agent or adhesive for holding the finely-divided additives within the filter has been proposed but such a remedy is generally unacceptable since it both increases the complexity of the manufacturing operation and tends to mask the additive so that the effectiveness of the filter is greatly reduced.

Therefore, it is readily apparent that an improvement in the tobacco smoke filter art which would permit the substantial reduction or complete elimination of aldehyde vapors and other irritating gaseous constituents from tobacco smoke without at the same time adversely affecting the flavor and aroma of the smoke would represent a substantial stride forward. Ideally, this improvement should use a material and/ or method that is inexpensive, reliable and commercially available. Furthermore, the filter should be capable of removing only the deleterious vapors found in tobacco smoke, and the vapors removed should be chemically reduced so that they will not be eluted at a later time due to a change in the filter structure or environment. The process whereby the filter is produced must also be compatible with existing manufacturing equipment and capable of being applied evenly to the filter media at the speeds and low per unit cost demanded by the industry.

According to the present invention a convenient and effective method has been found by which a tobacco smoke filter can be constructed for the selective removal of aldehyde type vapors from tobacco smoke. This method consists of coating or otherwise dispersing selected water-soluble hydrazides onto the filtering material from which the tobacco smoke filter element is formed. The aldehyde vapors are reduced chemically to an inert material upon its contact with the water-soluble hydrazides in the filter thereby preventing the irritating aldehydes from reaching the smokers mouth.

Therefore, an object of this invention is to provide a new and improved tobacco smoke filter unit for selectively removing certain aldehyde type vapors from effiuent tobacco smoke.

Another object of this invention is to disclose certain water-soluble chemical additives for tobacco smoke filters which will substantially eliminate aldehyde type ciliarydepressant constituents found in tobacco smoke.

Yet another object of this invention is to disclose certain Water-soluble hydrazide additives for use with a tobacco smoke filter which Will chemically reduce the concentration of ciliary-depressants, such as acrolein and aldehydes, from the tobacco smoke drawn through the filter.

Still yet another object of this invention is to disclose a new tobacco smoke filter tow, and a method of manufacturing the same, which contains watersoluble hydra zides capable of chemically reducing the aldehyde vapors found in tobacco smoke to a harmless material.

A further object of this invention is to describe a cigarette filter having water-soluble hydrazides coated therein for selectively removing acrolein vapors from tobacco smoke through a chemical reaction technique.

A still further object of this invention is to describe a method and process of manufacturing a coated cigarette filter from a cellulose acetate tow 'which contains watersoluble monomeric hydrazide additives capable of removing lowrnolecular-weight aldehydes from tobacco smoke by a chemical reaction rather than by physical adsorption.

These and other objects and advantages of this invention will be more apparent upon reference to the following description, appended claims, specific working examples, and drawings wherein:

FIGURE 1 is a perspective, with portions thereof broken away, of a cigarette having attached thereto a filter tip prepared in accordance with this invention; and

FIGURE 2 represents a greatly magnified cross sectional view of a plurality of filamentary elements coated with water-soluble monomeric hydrazides in accordance with the teaching of this invention for selectively removing aldehyde type constituents from effluent tobacco smoke.

As set out hereinabove, this invention. in its broadest aspects involves the use of certain water-soluble monomeric hydrazides as a coating in tobacco smoke filters for selectively removing low-molecularweight aldehyde and acrolein vapors from eflluent tobacco smoke. The water-soluble monomeric hydrazides that have been found most etfective as a coating for selectively removing these vapors are those formed by the reaction of hydrazine with an aliphatic mono or dicarboxylic acid, as illustrated by the following types:

(I) A hydrazide of a monocarboxylic acid RiiNHNH:

R=C H where 12:1 to (II) A dihydrazide of a dicarboxylic acid R=C H where 11:0 to 10 Thus, several hydrazides can be employed in the operation of this invention.

Since the water-soluble monomeric hydrazides act through physical contact to chemically reduce the aidehyde type constituents of tobacco smoke, as shown in the following equation:

Ri INHNII RoHo acgirion. 1-120 it is very important that as much surface area of the hydrazides be exposed for contact with the tobacco smoke vapors as possible. This desired surface exposure can be obtained, for example, by adding the hydrazides to any general type of cigarette filtering material such as fibrous products of cotton, paper, regenerated cellulose, cellulose acetate, polyolefins or any other suitable carrier material having large surface areas that can be coated. However, the preferred carrier materials for the hydrazides are paper in a creped form and cellulose acetate fibers in the form of a crimped tow.

The addition of the monomeric hydrazides to the fibrous filtering material is accomplished by dissolving the hydrazides in water, treating the fibrous filtering material with the water solution, and evaporating the water. This treating of the fibrous filtering material with the water solution containing the hydrazide additives can be accomplished through a spraying, dipping, sponging, sprinkling or other suitable method whereby the solution is uniformly spread throughout the filter. As is apparent, this treatment of the fibrous filter material with the solution can best be performed while the material is in the form of a spread-out or bloomed tow although it can be performed at other points in the processing of the material into a filter. In fact, the incorporation of the additive may take place at any time prior to the final packaging of the tobacco smoke filter.

The fact that the monomeric hydrazides of this invention are water soluble and can thus be applied to give a uniform coating of the fibers with the hydrazide, as illustrated in FIGURE 2, is of utmost importance in the manufacture of filtered cigarettes of the type shown in FIGURE 1. By the use of these certain Water-soluble monomeric hydrazides no sifting, house-cleaning or eX- plosive conditions are produced as would occur if finelydivided solid additives were being employed. More importantly, the hydrazides are very evenly coated or distributed throughout the filter which produces a more efficient selective filter since it offers a better opportunity for the water-soluble aldehyde (i.e., acetaldehyde, acrolien, etc.) in the efllnent tobacco smoke to react with the hydrazides. This increased filtering action is due in part to the larger exposed area of the active monomeric hydrazides, but is also aided by the fact that the moisture in the smoke at least partly dissolves the water-soluble hydrazides on the filter thereby ofiering a better contact between it and the aldehydes. If desired, however, the Watersoluble hydrazides of this invention can be applied to the fibrous filtering material as a powder, or as a suspension in an organic liquid.

The amount of the monomeric water-soluble hydrazides needed to remove a significant amount of the aldehyde vapors from the efiiuent stream of tobacco smoke will vary depending on the type of hydrazide used and the manner in which it is applied to the carrier fibers, but in general will vary from 0.2 to 25 percent based on the dry weight of the carrier fiber with the preferred amount falling within the range of from 5 to 20 percent. As will be apparent to those working in the tobacco smoke filter art, this preferred range of from 5 to 20 percent of hydrazide additive is substantially less than the amount of the prior known additives required to remove a comparable amount of aldehyde vapors from tobacco smoke. This higher aldehyde removal per unit of additive placed in the filter is attributed to both the specific hydrazides used and the way in which they completely cover or coat the surface of the carrier material.

A further understanding of the invention will be had from a consideration of the following examples which are set forth to both illustrate the invention in general and to specifically illustrate certain preferred embodiments that can be used in actual commercial practice.

Example 1 A 170-mrn. length of 5 denier/filament -(d./ f.) crimped cellulose acetate filter tow which had 10,000 filaments and weighed approximately 1 gram (g.) was spread out to a width of approximately 15in. The tow was sprayed with a 25 percent aqueous solution of diglycolic acid dihydrazide (based on the dry weight of the cellulose acetate filter tow) and dried. The tow was then treated with 8 percent triacetin plasticizer, compacted, and wrapped with a paper tape to form a filter rod with a circumference equal to that of a standard domestic cigarette (25 mm.). The triacetin cured the filter tow thereby producing a rigid filter rod having the dihydrazide evenly dispersed throughout. The firm rod was cut into 20-mm. segments which contained 10 percent of diglycolic acid dihydrazide based on the dry weight of the tow. These 20-mm. segments were attached to king-size cigarettes and 20-mm. lengths of the cigarettes were cut off to retain the length of a commercial filter-tipped king-size cigarette.

The cigarettes were smoked with an automatic smoking device. The vapors which passed through the filters were collected and analyzed by gas chromatography. Table I lists the results obtained on. the diglycolic acid dihydrazide filter. Also listed are the results obtained from a 20-mm. cellulose acetate filter (5 d./f., 10,000 filaments) without any diglycolic acid dihydrazide.

A 170-mm. length of 5 d./f. crimped cellulose acetatetow which had 10,000 filaments and weighed approximately 1 g. was spread out to a width of approximately inches. The tow was sprayed with a 15 percent aqueous solution of malonyl dihydrazide and dried. The tow was then sprayed with triacetin (8.6 percent), compacted and wrapped with a paper tape to form a filter rod With a circumference of 25 mm. The rod was then allowed to stand until firm after which it was cut into -mrn. segments which contained 8.3 percent malonyl dihydrazide based on the dry weight of the tow. These 20-mm. segments were attached to king-size cigarettes and 20-mm. lengths of the cigarettes were cut 013? to retain the length of a commercial king-size cigarette. The cigarettes Were smoked and the vapors analyzed as in Example 1. The results are shown in Table II.

A 170-rnm. length of creped paper was spread out to a width of approximately 15 inches. The paper was dipped into a 15 percent aqueous solution of oxalic acid dihydrazide and dried. The paper was then compacted and wrapped with a paper tape to form a filter rod with a circumference of 25 mm. The rod was cut into 20-mm. segments which contained 6 percent of oxalic acid dihydrazide based on the dry weight of the paper. These 20- mm. segments were attached to king-size cigarettes and 20-mm. lengths of the cigarettes were cut off to retain the lengthof a commercial king-size cigarette. The cigarettes were smoked and the vapors analyzed as in Example 1. The results are shown in Table 111.

TABLE III ng. Found in Smoke From One Cigarette With A Cellulose Acetate Filter g. Found in Smoke From One Cigarette With An Oxalic Acid Dihydrazide Treated Paper Filter 1g. Found in Smoke From One Cigarette Without Filter Components Acetaldehyde Propionaldehyd Acrolein From the foregoing description it is readily apparent that the tobacco smoke tow and filter of this invention offers numerous detoxicatin-g advantages over those filters previously known and used in the cigarette industry. For example, not only is the filter a highly selective one which is capable of removing substantial amounts of the aldehyde vapors found in tobacco smoke as it moves through the interstices of the filter (over several hundred percent in one instance as compared to a filter without the additive), but the low-molecular-weight aldehydes removed by the water-soluble monomeric hydrazides are formed into a harmless complex which cannot later be eluted from the filter. Furthermore, the fact that the water-soluble hydrazide additives can be coated as an aqueous solution over the filter tow substantially eliminates the masking, sifting-out and house-cleaning problems heretofore so commonly encountered where finelydivided additives were used. The method and ease with which the water-soluble monomeric hydrazide additives can be evenly dispersed throughout a tobacco smoke filter also alleviates to a great extent the need for special equipment, processing steps and skilled personnel that has heretofore been required to produce a filter tow having an additive therein. Thus, the cost of producing the tow, as well as the filter units themselves, :by the method and with the materials of this invention is substantially reduced.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. For example, the water-soluble hydrazide coated filters may be used alone or in combination with other types of tobacco smoke filter elements. Therefore, the present embodiments are to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by the United States Letters Patent is:

1. As a new article of manufacture, a tobacco smoke filter element containing a filter additive, said additive being a monomeric water soluble hydrazide which will react with and render harmless substantially all aldehyde vapors in the tobacco smoke passing through said filter 70 element.

2. As a new article of manufacture, a tobacco smoke filter element containing a filter additive selected from the group consisting of diglycolic acid dihydrazide, malonyl dihydrazide, oxalic acid dihydrazide, or mixtures thereof which will react with and render harmless substantially all aldehyde vapors in the tobacco smoke passing through said filter element.

3. As a new article of manufacture, a tobacco smoke filter element containing between 0.2 and 25 percent by weight of a monomeric water-soluble hydrazide derived from the reaction of a mono or dicarboxylic acid, said monomeric hydrazide being characterized by being watersoluble and capable of chemically reacting and rendering harmless substantially all aldehyde vapors contained in the tobacco smoke passing through said filter element.

4. As a new article of manufacture, a tobacco smoke filter element of the fibrous type containing between 5 and 20 percent by weight of a monomeric water-soluble hydrazide coated thereon which will chemically react with and render harmless substantially all aldehyde vapors in the tobacco smoke passing through said filter element.

5. A tobacco smoke filter containing as an aldehyde removal material a water-soluble hydrazide filter additive, said additive composition being in accordance with the following general formula:

RQJNHNH,

where R= nH2n+1 and 72:1 to 1 0.

6. A tobacco smoke filter according to claim 5 wherein the amount of additive is from 0.2 to 25 percent by weight of the filter.

7. A tobacco smoke filter containing as an aldehyde removal material a water-soluble hydrazide filter additive, said additive composition being in accordance with the following general formula:

where n 2n and n=0 to 10.

wherein water soluble hydrazide additive is selected from the group consisting of diglycolic acid dihydrazide, malonyl dihydrazide, oxalic acid dihy-drazide, or mixtures thereof.

11. A tobacco smoke filter tow according to claim 13) wherein said additive is coated on said carrier material.

12. A tobacco smoke filter tow according to claim 9 wherein said carrier material is continuous fibers of cellulose acetate.

13. A tobacco smoke filter for selectively removing certain deleterious materials from tobacco smoke comprising interstices formed in said filter through which the tobacco smoke is drawn, and a monomeric water-soluble hydrazide additive located within said interstices so as to contact the tobacco smoke being drawn therethrough, said additive being selected so as to chemically react and form a cooperative complex with substantially all aldehyde vapors in the smoke.

14. A tobacco smoke filter of claim 13 wherein .the water soluble hydrazide additive composition is in accordanoe with the following general formula:

where R=C H and 11:1 to 1 0.

15. A tobacco smoke filter of claim 13 wherein the water soluble hydrazide additive composition is in accordance with the following general formula:

HzNHNPJR-%NHNH2 where R=C H and 11:0 to 10.

16. A tobacco smoke filter of claim 13 wherein from 0:2 to 25 percent by weight of the water soluble hydrazide additive is added to the filter. v

17. A tobacco smoke filter of claim 13 wherein said filter is formed of crimped cellulose acetate.

References Cited UNITED STATES PATENTS 2,815,761 12/1957 Shearer 131266 SAMUEL KOREN, Primary Examiner.

D. J. DONOHUE, Assistant Examiner. 

1. AS A NEW ARTICLE OF MANUFACTURE, A TOBACCO SMOKE FILTER ELEMENT CONTAINING A FILTER ADDITIVE, SAID ADDITIVE BEING A MONOMERIC WATER SOLUBLE HYDRAZIDE WHICH WILL REACT WITH AND RENDER HARMLESS SUBSTANTIALLY ALL ADLEHYDE VAPORS IN THE TOBACCO SMOKE PASSING THROUGH SAID FILTER ELEMENT. 